#    This file is part of the Minecraft Overviewer.
#
#    Minecraft Overviewer is free software: you can redistribute it and/or
#    modify it under the terms of the GNU General Public License as published
#    by the Free Software Foundation, either version 3 of the License, or (at
#    your option) any later version.
#
#    Minecraft Overviewer is distributed in the hope that it will be useful,
#    but WITHOUT ANY WARRANTY; without even the implied warranty of
#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General
#    Public License for more details.
#
#    You should have received a copy of the GNU General Public License along
#    with the Overviewer.  If not, see <http://www.gnu.org/licenses/>.

import os
import os.path
import tempfile
import shutil
import logging
import stat

LOG = logging.getLogger(__name__)

## useful recursive copy, that ignores common OS cruft
def mirror_dir(src, dst, entities=None):
    '''copies all of the entities from src to dst'''
    if not os.path.exists(dst):
        os.mkdir(dst)
    if entities and type(entities) != list: raise Exception("Expected a list, got a %r instead" % type(entities))
    
    # files which are problematic and should not be copied
    # usually, generated by the OS
    skip_files = ['Thumbs.db', '.DS_Store']
    
    for entry in os.listdir(src):
        if entry in skip_files:
            continue
        if entities and entry not in entities:
            continue
        
        if os.path.isdir(os.path.join(src,entry)):
            mirror_dir(os.path.join(src, entry), os.path.join(dst, entry))
        elif os.path.isfile(os.path.join(src,entry)):
            try:
                shutil.copy(os.path.join(src, entry), os.path.join(dst, entry))
            except IOError as outer: 
                try:
                    # maybe permission problems?
                    src_stat = os.stat(os.path.join(src, entry))
                    os.chmod(os.path.join(src, entry), src_stat.st_mode | stat.S_IRUSR)
                    dst_stat = os.stat(os.path.join(dst, entry))
                    os.chmod(os.path.join(dst, entry), dst_stat.st_mode | stat.S_IWUSR)
                except OSError: # we don't care if this fails
                    pass
                shutil.copy(os.path.join(src, entry), os.path.join(dst, entry))
                # if this stills throws an error, let it propagate up

# Define a context manager to handle atomic renaming or "just forget it write
# straight to the file" depending on whether os.rename provides atomic
# overwrites.
# Detect whether os.rename will overwrite files
with tempfile.NamedTemporaryFile() as f1:
    with tempfile.NamedTemporaryFile() as f2:
        try:
            os.rename(f1.name,f2.name)
        except OSError:
            renameworks = False
        else:
            renameworks = True
            # re-make this file so it can be deleted without error
            open(f1.name, 'w').close()
del tempfile,f1,f2
doc = """This class acts as a context manager for files that are to be written
out overwriting an existing file.

The parameter is the destination filename. The value returned into the context
is the filename that should be used. On systems that support an atomic
os.rename(), the filename will actually be a temporary file, and it will be
atomically replaced over the destination file on exit.

On systems that don't support an atomic rename, the filename returned is the
filename given.

If an error is encountered, the file is attempted to be removed, and the error
is propagated.

Example:

with FileReplacer("config") as configname:
    with open(configout, 'w') as configout:
        configout.write(newconfig)
"""
if renameworks:
    class FileReplacer(object):
        __doc__ = doc
        def __init__(self, destname):
            self.destname = destname
            self.tmpname = destname + ".tmp"
        def __enter__(self):
            # rename works here. Return a temporary filename
            return self.tmpname
        def __exit__(self, exc_type, exc_val, exc_tb):
            if exc_type:
                # error
                try:
                    os.remove(self.tmpname)
                except Exception, e:
                    LOG.warning("An error was raised, so I was doing "
                            "some cleanup first, but I couldn't remove "
                            "'%s'!", self.tmpname)
            else:
                # copy permission bits, if needed
                if os.path.exists(self.destname):
                    shutil.copymode(self.destname, self.tmpname)
                # atomic rename into place
                os.rename(self.tmpname, self.destname)
else:
    class FileReplacer(object):
        __doc__ = doc
        def __init__(self, destname):
            self.destname = destname
        def __enter__(self):
            return self.destname
        def __exit__(self, exc_type, exc_val, exc_tb):
            return
del renameworks